Massive Right-handed Neutrinos in B Decays

In this paper, we present the differential decay distributions for $\bar{B}\to D^{(\ast )}\mathrm{\ell }\bar{X}$ decays with a massive right-handed neutrino in the low-energy effective field theory framework and show how the massive effects of the RH neutrinos can explain the positive value of the difference in forward-backward asymmetries, $\mathrm{\Delta }{A}_{\text{FB}}\equiv A_{\text{FB}}^{\mu }-A_{\text{FB}}^e$, tentatively inferred from Belle data. We also make predictions for $q^2$ dependent angular observables to motivate future measurements.